As the data service increases, the conventional SDH (Synchronous Digital Hierarchy) transmission technology also has corresponding advancement. The Next Generation SDH (NG SDH) technology represented by virtual concatenation, LCAS (Link Capacity Adjustment Scheme) and GFP (Generic Framing Procedure) accelerates the evolution of conventional SDH devices mainly-designed for TDM service to the direction of MSTP (Multi-Service Transmission Platform).
In MSTP devices, switching of data service between different boards can be implemented through adding data switching function, and accordingly, the demand of incremental data service can be satisfied.
At present, almost all data switching and TDM cross-connecting are implemented on different boards; some solutions can accomplish data/TDM integrated switching, but these solutions have some problems, the most important one of which is they need line boards to implement identification of data service, and even de-mapping and de-encapsulation; in this way, the virtual concatenation service in different lines can not be supported.
FIG.1 shows a data switching solution of the prior art. In this solution, a data service processing unit transmits the data as required to be switched to a data switching unit via data bus to implement switching; a line unit implements separation of data service and TDM service on TDM (such as SDH/SONET) lines, so that the data service gets to the data switching unit via the data bus to be switched, and the TDM service is crossed by a cross-connecting unit.
The data switching unit may has functions of encapsulating and mapping data service to SDH container, here the data switching unit is connected with the cross-connecting unit by the bus.